Looks like it needs stronger wooden components all round - thicker uprights (telephone poles) and bigger cross-section members. You need to be careful how you deal with the base of the uprights too - if they just go straight into the ground they will, as you've seen, rot through.

My husband has built an open fronted implement shed totally by hand ie no power tools. He is currently putting up a large pole barn, although this time he has made the concession of using a battery powered drill. It is actually oversturdy to my mind as well as too large, but it shows it can be done, and by one somewhat decrepit person working on his own. He had no special skills for building but learnt as he went along.

So for your shed, it needs to come right down (lots of good firewood there) and a new one, whether wooden construction or metal kit, put up in its place.

You will though have plenty of other things to do when you buy your new land.For help, if you have room in the house or have a caravan available, you could get HelpXers in - look them up, it can work well.

It's actually very solid and not about to fall down. The timber, apart from the uprights is all good and the felt lining under the roof is intact. There's only the damage that that picture shows, a few of the roofing plank have cracked, the rest is intact. It's not old, may even have been put up on the pee as you cant push or rock it anywhere.

I don't really need a pole barn but as it's there I thought make it last a bit longer. It might serve some future use. I'm presuming that the neighbours will be the current owners and they are just selling off some of their assets as a new right of way is being created for access.It would be very difficult to get anything other than a small 4WD or tractor to the land, certainly not any kind of bulk carrying vehicle. I have neither 4WD or tractor. (There's no road access and I cycle along a bridle way to get there otherwise it's across fields).

I doubt that it is concreted in as the soil is heavy clay and expands and contracts massively depending on season. I'm presuming it just lilted due to ground movement. Once the ground is sodden it maybe less solid. The ground is like concrete at the moment.

I reckon the easiest would be to gently lift up the roof timbers (you may need to remove the roof cladding first) a few inches with a jack or even tele handler, temporarily holding them in place with wooden props or Acrow props. Repair, renew or refix the columns (depending on condition then let the roof timbers back onto the new columns and repair/refix timbers as you go.

If you're going to do all that and try and keep safe you might as well take the flipping lot down, that's faaaar too much carry on. You need the poles set in concrete with damp proofing thick plastic around the bases or set in metal shoes set in the ground / concrete.

Barns are good to have though, useful, and if you can get it down to the basic structural elements then it may be worth correcting, think I'd put something quicker to cover the roof though, wrinkley tin or the like, something inexpensive.

Definately a renew and not a refurb, salvage the materials as you go so when you feel the notion coming on you can to do some man stuff there'll be no stopping you

Just my experience concreting posts in makes them sweat funny how city fencing lasts <10 years when stock fencing lasts 30 + one uses concrete one doesn't personally I would use 2 acrows jack up slightly each side of upright take out replace move on to the next SIMPLES !